Dr Makhlin on Data to Support the Use of FES-PET/CT in Breast Cancer Management

“If there is ER positivity on the [FES-PET/CT] scan that correlates with symptoms, it essentially helps support progression of disease.”

Igor Makhlin, MD, an assistant professor of clinical medicine in the Division of Hematology-Oncology in the Department of Medicine at the University of Pennsylvania Perelman School of Medicine, as well as clinical leader of Flatiron Assist Breast Pathways and director of the Metastatic Tumor Board at Penn Medicine, discussed the use of 18F-fluoroestradiol (FES)–PET/CT as a specialized tool for aiding in the diagnosis and management of estrogen receptor (ER)–positive breast cancer.

Makhlin argued that although determining disease histology through biopsy remains the standard of care, several robust studies have now established that FES-PET/CT provides high sensitivity and specificity when identifying ER-positive disease. This technological advancement serves as the foundation for a more nuanced approach because of its ability to predict patient response to endocrine therapy, he said.

According to Makhlin, the predictive power of this imaging tool is a cornerstone of its clinical utility. Research indicates that a lack of FES uptake on a scan serves as a reliable indicator of a poor response to endocrine treatments, he reported. This information allows oncologists to make more informed decisions about whether to pursue certain systemic therapies, he stated.

Makhlin also emphasized that this utility is especially critical during the early-stage workup. In scenarios where standard imaging reveals suspicious features that are physically inaccessible for biopsy, a positive FES-PET/CT scan for a distant lesion can entirely change treatment decisions, he noted. Instead of proceeding with invasive curative-intent surgery or radiation, the medical team can transition the patient to a metastatic paradigm, thereby avoiding unnecessary procedures and moving the patient directly to systemic therapy, he elaborated.

To supplement this diagnostic role, Makhlin highlighted the value of FES-PET/CT in the metastatic setting. For patients with proven disease who are currently undergoing treatment, changes in bloodwork results or physical symptoms may arise that are not adequately captured by conventional scans, he continued. In these instances, FES-PET/CT could characterize the underlying disease activity, he explained. If the scan reveals ER positivity that correlates with the patient’s symptoms, it provides critical evidence supporting a diagnosis of disease progression, he added.

However, Makhlin noted that a negative FES-PET/CT scan does not imply the absence of cancer. Instead, it may indicate that the tumor’s receptor expression has shifted from ER-positive to ER-negative, often as a result of selection pressure during treatment, he concluded.